HoldRest is an attribute which specifies that all but the first argument to a function are to be maintained in an unevaluated form.

LinkLaunch["prog"] starts the external program prog and opens a MathLink connection to it.

LinkRead[link] reads one expression from the specified MathLink connection. LinkRead[link, h] wraps h around the expression read before evaluating it.

LinkWrite[link, expr] writes expr to the specified MathLink connection.

Switch[expr, form_1, value_1, form_2, value_2, ...] evaluates expr, then compares it with each of the form_i in turn, evaluating and returning the value_i corresponding to ...

You can use most of the list operations discussed in "Lists" on any kind of Mathematica expression. By using these operations, you can manipulate the structure of expressions ...

You can use the keyboard to move the cursor forward or backward one character or one word at a time. You can also delete the character or word to the right or the left of the ...

Choose Insert > Table/Matrix > New. Use the dialog box that pops up to create a matrix. Suppose the entry in the top-left position is selected.

$FrontEndInitializationFunction is a function that you can assign to execute when the front end link is first established by ConnectToFrontEnd[].

TetGenCreate[] creates an instance of a TetGen expression.